This invention relates to a clamping device, especially for a plug-in coupling, with a substantially cylindrically shaped housing, a clamping element mounted to slide axially therein and an actuating part which is arranged on the rear side of the housing and is coupled to the clamping element for the axial displacement and is biased by a compression spring and can be actuated by means of a manual lever.
Such a clamping device for a plug-in coupling is known from DE 3 518 019 C2, wherein this plug-in coupling is especially in the form of a so-called test connector for pressure-tight connection to hydraulic lines, gas bottles and similar fluid lines. The actuation when connecting to the article carrying fluid, for example a connection nipple, pipe union or the like, is effected by a manual lever, which extends essentially axially to the cylindrically shaped housing. Single handed operation for coupling or uncoupling the plug-in coupling, with simultaneous actuation of the clamping device can thus be effected through this manual lever, which is preferably adapted to the human hand. The pivotally articulated manual lever at the rear end of the coupling housing presses against the rear end of a clamping piston, serving as the clamping element, via a pin, the piston having radially spreading clamping grippers or clamping jaws at its front end, which engage behind the corresponding profiling of the connector, (e.g. connection nipple) in the clamping position. This clamping piston is furthermore biased by a compression spring, which holds the clamping grippers spread when the manual lever is released, so that the plug-in coupling is hereby biased into and held in its engaged position.
The spring force of this compression spring should be as high as possible, in order to hold the clamping element or clamping jaws in the engaged position of the plug-in coupling with as high a force as possible. However, this involves a relatively high actuating force over the path of actuation (axial stroke) of some centimetres, so that a compromise is mostly made between biasing spring force and the actuating force to be applied to the manual lever. In particular an increase in the spring force of the compression spring is generally ruled out, since the actuation of the compression spring shown in this reference can lead to canting of the pressure spring through a pin engaging at the side. In addition the lever ratios in this plug-in coupling are restricted by the lateral arrangement, so that the maximum actuating forces is also limited.
Actuation of the basically similarly constructed plug-in coupling is known from WO 89/07729 by a rear end pressure knob of about the size of the palm of a hand, with which a compression spring can be actuated to connect up or release the plug-in coupling. However, the operating forces which can be applied are small. A likewise similarly constructed plug-in coupling is furthermore known from WO 89/11059, wherein the actuation of the clamping piston serving as the clamping element is effected via an eccentric. Although the lever ratios are more favourable here, the manufacture of this eccentric is very expensive. In addition it is a disadvantage with all these clamping devices that the bias force in the clamping position (clamping jaws locked) is lowered on account of the relatively large axial stroke required for actuation, while the spring force to be overcome is at its highest on actuating the clamping device, since the compression spring has to be compressed more or less completely or even until it is solid.
The invention is accordingly based on the object of improving a clamping device of the kind defined in respect of the axial clamping force acting on the clamping element with a smaller actuating force and smaller manufacturing cost.